An ontology is a formal representation of knowledge within a domain that is machine-readable, but also understandable to humans. It typically includes unique hierarchically arranged concepts that have specific attributes and are semantically related to other concepts. Dissanayake, P. I., Colicchio, T. K., & Cimino, J. J. (2020). Using clinical reasoning ontologies to make smarter clinical decision support systems: a systematic review and data synthesis. Journal of the American Medical Informatics Association, 27(1), 159-174. https://doi.org/10.1093/jamia/ocz169